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ANTIVIRAL AGENTS FOR THE PREVENTION AND TREATMENT OF INFLUENZA. Neuraminidase inhibitors. Viral hemagglutinin binds to cellular sialic acid. Binding to Sialic Acid. B. Engulfing Virus. C. Uncoating and Virus Replication. Neuraminidase and viral spread.
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ANTIVIRAL AGENTS FOR THE PREVENTION AND TREATMENT OF INFLUENZA
Viral hemagglutinin binds to cellular sialic acid • Binding to Sialic Acid B. Engulfing Virus C. Uncoating and Virus Replication
Neuraminidase and viral spread Permits release of progeny viruses from infected host cells Prevents aggregation of newly formed viral particles Allows virus to penetrate the mucus of the respiratory tract Calfee DP, Hayden FG. Drugs 1998; 56: 537-553. Colman PM. Protein Sci 1994; 3: 1687-1695.
Neuraminidase inhibitors: Mode of action Progeny virusesreleased from cell NeuraminidaseInhibition Engulfing Virus Replication Neuraminidase inhibitors block the active site of the enzyme and prevent release of virus from infected cells
Neuraminidase: A conserved site of action Type A+B H1N1 H2N2 H3N2 H5N1 H9N2 H7N2 Neuraminidases inhibitors are active against influenza viruses carrying all the known hemagglutinin and neuraminidase subtypes
Influenza neuraminidase inhibitors Zanamivir Oseltamivir Influenza A and B Influenza A and B Oral inhalation of powder Oral capsules or liquid suspension Effective for treatment and prophylaxis Effective for treatment and prophylaxis zanamivir (1980) oseltamivir (1996) structure-baseddesign 2000s
Zanamivir OH HO H O HO CO2H CH3CONH NH2 NH NH
Oseltamivir Oxygen Nitrogen
The prodrug concept and oral bioavailability Prodrug “masks” polarity of active form Rapid hepatic conversion to active form Bioavailability: at least 75% High plasma concentrations O O O O O OH Ester hydrolysis HN HN NH2·H3PO4 NH2 O O Oseltamivir phosphate Oseltamivir carboxylate
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